Fuse detonating mechanism



F. L. EVERETT FUSE DETONATING MECHANISM May 27, 1952 2 SHEETS-SHEET 1 Filed Dec. 26, 1945 w W W n 4 y m May 27, 1952 F. EVERETT FUSE DETONATING MECHANISM 2 SHEETS-SHEET 2 Filed Dec. 26, 1945 JIWMVTM Franklin L Ev E1" EH Patented May 27, 1952 UNITED STATES FATENT ()FFICE FUSE DETONATING MECHANISM Franklin L. Everett,'Ann Arbor, Mich., assignor to the United States of America as represented by the Secretary of War Application December 26, 1945, Serial No. 637,184 3 Claims. (01. 102 19) The present invention relates generally to explosive shells or projectiles, and more particularly to an impact responsive inertia operated fuse, either point located or of the base type. It is here applied particularly to the type which is automatically armed by acceleration of the proectile when in flight, to be operated at the point of impact with the target.

It is an object to make novel use of the snapaction of a Belleville spring type washer in passing and re-passing its dead center in conjunc' tion with a striking head or detonator of a fuse.

An important aim is to simplify structural features and reduce to a minimum number the parts employed, to the end that the detonating unit may be manufactured at low cost, and the parts readily assembled and effectively retained in the prepared safety condition prior to firing.

It is another aim to present novel safety devices to render the detonator inoperative to prevent accidental percussion that might otherwise occur due to rough handling before insertion within the projectile, and to prevent detonation otherwise before and during flight of the pro- .iectile before impact.

In the accompanying drawings one preferred example and a modified form illustrate the physical embodiment of the invention, from which additional objects, advantages and features of invention in the combination, arrangement and specific structure will be apparent or understood, but it will be understood that various changes and alterations may be made in these exemplifying drawings without departing from the spirit of the invention.

Figure 1 is a longitudinal section of the unit, with the Belleville washer in its initial, slightlycompressed, normal loaded position, and the striking-head or cletonator in unarmed position preparatory to firing.

Figure 2 is a view similar to Figure 1 showing the parts in fired position, with the firing pin of the detonator puncturing the primer or squib.

Figure 3 is a section of a modified form of the invention with the unit in safety disarmed position as it would be in the chamber of the gun before firing.

Figure 4 is a similar view after firing the device of Fig. 3, with the unit automatically armed by set back, and showing the unit as it would be when the projectile leaves the muzzle of the gun.

Figure 5 shows the modified unit in detonating position.

Figure 6 is a cross section on the line E--t of Fig. 3. a

Figure 7 is a fragmentary section of a projectile with the fuse of Figures 3-6 therein.

Figure 8 is a fragmentary longitudinal section of a modification of the forward detent means of Figs. 3-6.

Referring particularly to Figures 1 and 2, there is shown a substantially cylindrical hollow holder or casing H, having an integralhead [2, within which the primer i3 is mounted in a concentric seat recess M formed in the head. From this recess a flash port l5 opens forward concentrically through .the head I2. The casing is enlarged and interiorly threaded at its rear part. The rear side of the holder is closed by a conical back plate It having an externally threaded back-v wardly extended wall I! screwed into the in-- terior threads of the holder or casing. 7

It should be noted that the concave side of the plate I6 is toward the head [2. The side wall of the casing is formed with a shoulder I8 against which a shoulder IQ of the wall [1 abuts, the geometrical projection of the cone of the plate It being located inwardly of this shoulder t8 and having annular concentric ribs or knobs 20 slightly raised thereon, near the cylindrical wall of the casing and at the inner part of the plate, to support a Belleville spring 2i, the perimeter of which is set in a channel 22 formed in the wall of the case to receive this spring edge loosely, so that the spring may be sprung from normal initial form as in Fig. 1, to an inverted form as in Fig. 2. The plate I6 is formed with a reduced substantially cylindrical tubular rearward spring housing 23 opening through the plate [6 concentrically and having slidable therein a heavy cylindrical firing head or plunger 24 having on its forward end a firing pin 25, adapted to engage the primer I3 by forward movement.

The channel 22 affords at its forward side a seat 26 forthe extreme edge of the spring 2|. In the condition shown in Fig. 1 the spring is slightly compressed between the seat 26 and the rib 20, and under an initial normal tension to aid in retaining the mechanism against accidental operation that might otherwise occur during rough handling of the unit; or that might occur during handling of the projectile with the enclosed detonating unit mounted therein. In this position the Belleville spring has been compressed or deflected nearly to the position corresponding to, and assumed by, this spring when it is sustaining its maximum load; and the washer is held under tension against the inner annular flaring rib 20 of the holder.

The rear side of the channel 22 is formed by 3 a seat flange 27, which for practicable assembly of the article may be a split steel ring square in section and set snugly in a groove 28 formed on the inner face of the enlarged wall of the case I, after placement of the spring 2 I.

The spring 2| is centrally apertured and set around the plunger 24, which is peripherally grooved as at 28 to snugly receive the edges of the opening in the spring.

The plunger 24 is a solid, cylindrical mass of suitable material of proper size and ample weight to perform the functions of a substantial plunger so that the integral firing pin 25 may penetrate the primer 2 as indicated in Figure 2.

To hold and retain the plunger, as well as the spring in disarmed, or safety position, Within or without the projectile, centrifugal detents 3D, in the form of pins having concentric heads 3| intermediately of their lengths, are radially slidable in bores 32 formed in appropriate enlargements of the wall of the housing 23. The inner ends of the centrifugal detents project into the housing and are urged inward by springs 33 confined between the heads 3| and collars 34 screwed into the outer ends of the bores and receiving the outer ends of the centrifugal detents slidably therethrough. The plunger 24 is peripherally grooved at 35 a distance inward of the groove 28 and receives the ends of the centrifugal detents therein so as to hold the plunger and the engaged part of the Belleville spring retracted to the rear armed position shown in Fig. l. The housing 23 is extended rearwardly in cylindrical form, its extremity being closed by a screw plug 36 by which a strong helical drive spring 31 in the housing is loaded to bear against the plunger 24 with a force which is somewhat less than sufficient to overbalance the force exerted, on the plunger by the spring 2|, but affords a component which, with the inertia of momentum developed in the plunger on impact of a projectile equipped with the fuse, will be sufficient to deflect the spring 22 past its dead center position, when reaction of the spring will cause it to snap to its inverted shape, delivering through the pin 25 a powerful blow to the primer |3, assuring its detonation. The drive spring is set in a recess 38 in the end of the plunger and another in the plug. By varying the distance the plug 36 is screwed in, the force of spring 31 can be adjusted.

This fuse may be set in a projectile base with the flash port in communication with a booster of a bursting charge, by usual conventional practices.

The springs 33 are proportioned to the moment of force developed in the centrifugal detents 33 at the acceleration developed by rotation of the projectile in flight, so that the springs are overcome by centrifugal force in the members 30 created by a spinning projectile, the nibs 29 are withdrawn from the groove 35 and the plunger is then held in firing position by the slightly compressed Belleville spring.

Upon impact of the projectile against its target, the plunger is projected and guided by the spring 2| along the axial line of the projectile and the firing pin punctures the primer as indicated in Figure 2. Here it will be seen that the Belleville spring in guiding the plunger has snapped beyond its dead center of action, and the resiliency of material in the spring disc assists in the movement of the plunger to fire the fuse or primer.

In the modification of Figs. 3-5 the drive spring 31 is omitted and the case consists of conic opposed front and rear halves 40--4 I which aresubstantially duplicates except that the peripheral wall 42 of the one screws into the corresponding wall 43 of the other. The wall 42 is rabbeted to form a front seat shoulder 44 and channel at 45, while the opposite half has a flat 46 against which the wall 42 abuts, and extending inward sufliciently to serve as a rear seat for the peripheral edge of the Belleville spring 47 which may be similar to the one 2| before described.

Each of the two case halves is formed with a concentric boss 48, externally threaded at its extremity and having cylindrical bores 49 therethrough of a diameter to receive slidably a plunger 58 of about the same size as the one first described. This plunger however requires only a single groove therearound as at corresponding to the one 23 and similarly receiving the edges of the opening in the Belleville plate 47. This plunger has a firing pin 52 similar to the one 25 and coacts with a primer 53 set in the outer part of the bore through the forward half of the case. The boss 48 on this half of the case is partly closed by an annular screw collar 54 having a flash port 55 therein. The opposite rear half of the case has its boss closed by a simple screw cap 56.

Each of the bosses 48 includes lateral enlargements 5? radially bored and having spring loaded centrifugal detents therein similar to the ones 30. The radial bores 58 in the rear case half are so located and the length of the plunger 53 is such' that when the latter is at a forward safe position with the Belleville spring dished toward the front but short of the front conical wall of the case as in Fig. 3, the inner fingers 59 of the rear centrifugal detents 60 may project behind the plunger and retain the latter in stated forward position. The springs 6| of the rear centrifugal detents are of less strength than the springs 62 of the forward centrifugal detents 63 mounted in radial bores 64 of the front case half. The latter bores are so located that with the plunger 50 located at the forward safe position, the detents 65 of the centrifugal detents 66 will engage before the front end of the plunger, as in Fig. 3.

In the modification form of Figure 3 front centrifugal detents 63 with strong springs 62, and the rear detents 59 with comparatively weaker springs 6!, between them, retain the the detonator in disarmed safety position until the gun is fired.

After firing, before the projectile leaves the gun, detents 59 against weak springs 6| are retracted by initial centrifugal force and the detonator is moved by set-back to armed position of Figure 4, the resilient reversable Belleville washer being snapped through its dead center in this guiding movement.

After the projectile leaves the muzzle of the gun, under increased centrifugal force of the spinning projectile, the detents are retracted against the stronger springs E32, as in Figure 5, and under impact against the target the primer 4 is detonated as indicated.

In Figure 8 there is shown a further modification of the device of Figs. 3-5, in which the need of differentiated springs for the centrifugal detents at front and rear is obviated.

In this instance the case is the same as in Figs. 3-5, and the lower centrifugals the same. The plunger is formed with a concentric channel 65 on its top close to its periphery, and unloaded centrifugal detents fit are mounted slidably in in initial safe position. Each detent is formed with a reduced coaxial stem 61 at its inner end on which there is formed a concentric disc 68 spaced from the sliding outer body of the detent to engage in the channel 65 when the detent is at its inner limit and the plunger at its upper safe position.

The operation of the last described device is the same as that of the device in Figs. 3-5 but after setback of the plunger the centrifugal detents 66 are entirely free for radial movement. There is no possiblity of forward movement of the plunger until after retraction of the centrifugal detents 6B, setback of the plunger, and centrifugal function of the detents 6B.

The fuse will be useful generally in projectiles to be fired from rifled ordnance or, in the form shown in Figs. 1 and 2 may be used in projectiles otherwise rotated, or in which the fuse is rotated. As shown in Fig. '7 the rear boss part 48 may be screwed into the base plug 10 of a projectile 1| which thereby takes the place of the cap 56. Other installation expedients may be utilized, as need dictates. The flash part of my fuse will in any event be exposed to the bursting charge, an instancebeing shown in Figure 7.

I claim:

1. A fuse comprising a chambered case comprising two opposed conical parts joined at their bases and having tubular extensions at their apices, a Belleville washer spring set between said parts, a plunger fixed coaxially therein reciprocable in said extensions, a primer mounted in one of said extensions for engagement by the plunger at the adjacent limit of its reciprocation, centrifugal detents in the other of said extensions initially in detent relation to said plunger to hold the latter retracted responsive to flight forces in the projectile to release the plunger, said centrifugal detent being located to hold the plunger in a forward initial position short of said detonator, and forward centrifugal detent positioned to detain the plunger against forward movement from said initial position responsive to flight forces in the projectile greater than those efiectivev to operate the first named centrifugal detent, to clear the plunger for forward movement to engagement with the detonator.

2. A fuse comprising a chambered case comprising two opposed conical parts joined at their bases and having tubular extensions at their apices, a Belleville washer spring set between said parts, a plunger fixed coaxially therein reciprocable in said extensions, a primer mounted in one of said extensions for engagement by the plunger at the adjacent limit of its reciprocation, centrifugal detent in the other of said extensions initially in detent relation to said plunger to hold the latter retracted responsive to flight forces in the projectile to release the plunger, said centrifugal detent being located to hold the plunger in a forward initial position short of said detonator, and forward centrifugal detent positioned to detain the plunger against forward movement from said initial position responsive to flight forces in the projectile subsequent to response of the first named centrifugal detent, to clear the plunger for forward movement to engagement with the detonator.

.3. A fuse detonating mechanism for inclosure within a projectile which comprises the combination of a holder and a resilient and reversible Belleville washer mounted in the holder, a plunger having a forward detonation position and a rearward armed position mounted in the washer, first centrifugally actuated retractable means responsive to flight forces in the projectile for retaining the washer in an intermediate generally forward disarmed position, second centrifugally actuated retractable means responsive to flight forces in the projectile greater than those effective to operate the said first retractable means and positioned to detain the plunger against forward movement from the said disarmed position, the said washer being reversible under set-back for setting the plunger in armed position whereby impact forces are effective to move the said plunger forward of said disarmed position into detonating position.

FRANKLIN L. EVERETT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,290,680 Swanson Jan. 7, 1919 1,296,281 Gathmann Mar. 4, 1919 1,385,610 Flam July 26, 1921 2,162,719 Hay June 20, 1939 2 336 701 Rasmussen Dec. 14. 1943 

